[FFmpeg-user] Use ONVIF 1.0 NTP timestamp for synchronization

Carl Eugen Hoyos ceffmpeg at gmail.com
Sun Feb 12 15:30:37 EET 2017

2017-02-12 10:03 GMT+01:00 Jan Koppe <jan.koppe at wwu.de>:

> I've dug a bit into the rtp protocol (very basic understanding only for
> now) and saw that our cameras support the ONVIF 1.0 standard,
> which says that a wallclock NTP timestamp is sent within the RTP
> header. As far as I can see this would be ideal: the university is
> running a dedicated NTP server to which all devices synchronize, so
> if we could leverage this timestamp to sync up audio and video our
> issues would be solved (there will probably still be a small offset, but
> that should be much more consistent and can be fixed easily).

I suspect ONVIF is not supported by FFmpeg (the wikipedia page
contains hints that this is a pure marketing thing though, all the
better if it really works).

> At this point I am completely stuck: I tried capturing in separate
> processes, a single process with multiple inputs, different -vsync
> parameters but have not got it to work at all.

(Command line and complete, uncut console output missing.)

> It seems that ffmpeg is
> not capable of detecting these timestamps.

Patch welcome!

Carl Eugen

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